Keyboard instrument

ABSTRACT

Keys in a keyboard instrument can be depressed in a predetermined path and have secured to them a guide member of synthetic plastic material for movement with the keys, each guide member having an elongated slot which extends longitudinally of the respective key and into which one guide pin mounted adjacent to the key extends with an end portion so as to guide the key during movement as it is being depressed or returns to its initial position.

United States Patent ['1 Schutze I [451 July 24, 1973 KEYBOARD INSTRUMENT [76] Inventor: Rainer Schutze, Muehltalstr. 128,

Heidelberg, Germany [22] Filed: Feb. 3, 1972 21 Appl. No.: 223,205

[30] Foreign Application Priority Data Farny 84/433 Wood et al. 84/436 Primary ExaminerRichard B. Wilkinson Assistant Examiner-Lawrence R. Franklin Attorney-Michael S. Striker [57] ABSTRACT Keys in a keyboard instrument can be depressed in a predetermined path and have secured to them a guide member of synthetic plastic material for movement with the keys, each guide member having an elongated slot which extends longitudinally of the respective key and into which one guide pin mounted adjacent-to the key extends with an end portion so as to guide the key during movement as it is being depressed or returns to its initial position.

11 Claims, 4 Drawing Figures ii/171% ll:

KEYBOARD INSTRUMENT BACKGROUND OF THE INVENTION such lateral displacement, keyboard instruments are provided with guide pins which extend in elongated holes or slots formed in the respective keys, and these slots are usually internally clad with cloth, felt or the like. It has been proposed to substitute for the cloth or felt a sleeve of synthetic plastic material.

This prior art approach is of course very widely used but it is possessed of certain disadvantages which makes improvement desirable. On the one hand, the actual making of the elongated slots in the respective keys is relatively expensive because it is time consuming and therefore involves increased labor costs. On the other hand, and perhaps even more importantly, the keys are often made of a material such as wood which contracts or expands in response to changes in the ambient environment, that is changes in the ambient humidity or temperature. When this occurs, the dimensions of the slots in which the pins are guided can change and the free movement of the keys in uniform manner is influenced either by the fact that excessive lateral displacement of the keys can occur or by the fact that the keys can become stuck that is cannot be moved or can be moved only with difficulty.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to overcome the above-mentioned disadvantages.

More particularly, it is an object of the present invention to provide in a keyboard instrument, an arrangement which will avoid the disadvantages outlined with respect to the prior art.

A concomitant object of the invention is to provide such an arrangement which is inexpensive to produce and to install.

Another object of the invention is to provide such an arrangement in which proper guidance of each key is assured, irrespective of changes in ambient conditions.

In pursuance of these and other objects which will become apparent hereafter, one feature of the invention resides, in a keyboard instrument, in a combination of at least one elongated key which is depressable in a predetermined path, a guide member of synthetic plastic material which is secured to the key for movement therewithand which has an elongated slot extending in longitudinal direction of the key. There is further provided at least one guide pin mounted adjacent the key and having an end portion extending into the slot for guiding the key during movement of the same in its path.

By making the guide member of synthetic plastic material I assure that it is largely free of dimensional changes in response to variations in ambient conditions, that is either in conditions of humidity or temperature. Furthermore, such a guide member can be produced inexpensively and eliminates the need for forming an elongated slot in the respective key, an operation which had to be carried out with precision and was, as pointed out above, time consuming and therefore expensive.

If the guide member is secured on the key itself, intermediate the opposite ends thereof, then the key may be formed with a depression or bore of cylindrical configuration which can be produced very simply and rapidly and without the time consuming care heretofore required for formation of the elongated slot. On the other hand, the guide member can also be such that that portion of it which has the elongated slot therein, extends beyond one end of the key, usually the rear end where the key is hinged, in which case the formation of the bore in the key is not necessary at all.

It is particularly advantageous if the guide member is provided with at least two projections which can be inserted into corresponding bores formed in the key, such bores again being cylindrical and being capable of being formed rapidly and inexpensively. The engagement and retention of the projections can be by a friction fit, although it is of course also possible for instance to utilize adhesive means to retain the projections in the associated bores.

The portion of the guide member which is formed with the elongated slot may either be a center portion of the guide member, in which case at opposite ends of the center portion there will be end portions each of which may be provided with one of the projections, or it may be one of two end portions of the guide member in which case the other end portion may be provided with the projections. Naturally this does not exhaust the possibilities for the contour and configuration of the guide member, as will be appreciated.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims.

The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary vertical longitudinal section through one key of the keyboard instrument, provided with the present invention;

FIG. 2 is a bottom plan view of the key in FIG. 1;

FIG. 3 is a bottomplan view of another key provided with a further embodiment of the invention; and

FIG. 4 is a top-plan view of still another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS instance of a piano, a spinnet, or the like. In such keyboard instruments, the rear end of the keys (that is the end which is not shown in FIG. 1 but would be on the left hand side of the drawing) is hinged so that the key can be depressed in FIG. 1 downwardly, when operated, that is when struck for playing purposes. Such keys must be also provided with lateral guidance so that they cannot move laterally of the path in which they are displaced between the illustrated rest position and the depressed playing position. They are therefore guided by means of guide pins 3 of which usually one is associated with each key. In conventional manner, such guide pins 3 are mounted in an elongated member 2 which extends underneath the keys 1 over the entire width of the keyboard, that is beneath all of the keys 1 of the keyboard.

Conventionally, these guide pins extend into elongated slots (elongated in the direction of elongation of the key 1, i.e. from left to right in FIG. 1), which are formed in the key itself. The present invention, however, avoids the disadvantages attendent upon the utilization of such a slot as have been outlined above, by providing a guide member 4 of synthetic plastic mate rial. In particular, the synthetic plastic material utilized must be hard and must be capable of sliding, that is it must have a low coefficient of friction, and by way of example it is pointed out that for instance nylon (polyamide), polyethylene, polyacetal resin etc. can be utilized for this purpose.

In the embodiment of FIGS. 1 and 2, the guide member 4 has one end portion which, as is clearly evident from FIGS. 1 and 2, is provided with a pair (more can be used) of projecting portions 7. Another end portion extending from the one which is provided with projections.7 is of substantially loop-shaped configuration forming an elongated guide slot 5a whose elongation coincides with the direction of elongation of the key 1.

In the illustrated embodiment the portion provided with the slot 5a overlies a simple cylindrical recess or bore 6 formed in the underside of the key 1; this bore 6 does not, in itself, participate in guiding the guide pin 3, but is only provided to permit the up and down movement of the key 1 despite the presence of the pin 3. Lateral guidance of the pin 3 is provided by the longitudinally extending wall portions bounding the guide passage 5a in the loop-shaped end portion 5 of the member 4, as will be appreciated by comparing FIGS. 1 and 2.

It is evident that the member 4 can be secured to the underside of the key I in various different ways, including adhesively, or by means of screws or the like. If, however, the projections are provided as illustrated in the embodiment of FIGS. 1 and 2, a particularly simple way of securing the member 4 is afforded in that it is merely necessary to provide two bores in the underside of the key 1, which have a somewhat smaller diameter than the projections 7 so that the same can be forced into these bores and retained therein frictionally. Such bores can be provided in the key 1 at the same time as the bore 6 is formed, and this can be carried out in a single operation.

It is clear that with this construction it is immaterial whether the material of the key I itself undergoes expansion or shrinkage in response to fluctuations in ambient conditions, because the guide member 4 will not participate in these, and the dimensions of the slot 5a will therefore not be influenced by them.

In some types of keyboard instruments the lateral guidance of the keys is provided at the rear end of the keys, that is the end where the keys are hinged rather than the end where they are struck by the fingers of a player. In such a case, it is simply necessary to turn the guide member 4 of FIGS. 1 and 2 around, so that its loop-shaped end portion 5 projects outwardly beyond the rear end of the key 1, with the guide pin 3 then of course being provided rearwardly and below this rear end and extending into the slot 5a.

However, the embodiment in FIG. 3 shows that for such purposes the guide member can also be of different configuration. The guide member is here designated with reference numeral 4a and will be seen to be mounted on the underside of a key 10, at the rear end of the same. The portion provided with the projections 7 is secured to the key 1a, for instance in the same manner as in FIGS. 1 and 2, but the portion 5b of the member 4a extends outwardly beyond the rear end of the key 1a and is of bifurcated configuration so that it has a substantially U-shaped outline. In other words, wherein FIGS. 1 and 2, the portion 5 was loop-shaped, the portion 5b of FIG. 3 is substantially U-shaped and the rearward end of the slot is open rather than both ends being closed as in FIGS. 1 and 2. The guide pin 3 of course again extends into the slot as before.

Still another embodiment is illustrated in FIG. 4 by way of example. Rather than having the portion of the member 4 or 4a which is provided with the slot, configurated as an end portion of the member, it is possible to have this portion configurated as the intermediate portion located between two end portions. In FIG. 4, the guide member is designated with reference numeral 4b in toto, and has the two ends portions 4b each of which is provided with one of the projections 7. Located intermediate the end portions 4b is the interme diate portion 5' which is again formed with the elongated slot 5a here corresponding to the slot in FIGS. 1 and 2. The guide pin 3 of course again extens into the slot 5a.

The member 4b can be utilized in the same manner as the member 4 in FIGS. 1 and 2, and can, conceivably also be utilized in the same manner as the member 4a in FIG. 3.

In any of the exemplary illustrated embodiments, the lateral strip-shaped wall portions bounding the respective elongated slot may be somewhat elastically yieldable. In FIG. 4 this is shown by way of example, and the lateral wall portions bounding the slot 5a are designated with reference numeral 8. It will be seen that in this embodiment, the yieldable character is achieved in that the wall portions 8 are made narrower by constricting the width of the intermediate portion 5' so that due to the narrowness of the strip-shaped wall portions 8 the latter can yield to a certain extent.

It should be kept in mind that the illustrated embodi- V ments are purely exemplary and that quite evidently,

ary formation of an elongated slot directly in the material of the key 1.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the typesdescribed above.

While the invention has been illustrated and described as embodied in a keyboard instrument, it is not intended to .be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. i

' Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. In a keyboard instrument, in combination, at least one elongated key which is movable along a predetermined path, said key having (an external) a bottom surface; a guide member consisting of synthetic plastic material and secured to said key for movement therewith, said guide member having a guide portion outwardly adjacent to said (externallbottom surface and completely external from said key, said guide portion provided with an elongated slot'extending in the longitudinal direction of said key; a support; and a guide pin mounted on said support adjacent to said key and having a portion extending into-saidslot for guiding said key during movement along said path.

2. ln a keyboard instrument as defined in claim 1, said bottom surface being provided with a recess, and said guide member being mounted on said bottom surface with said slot extending across said recess.

3. In a'keyboard instrument as defined in claim 2, said recess being substantially cylindrical and having a diameter at least equal to the length of said slot.

4. In a keyboard instrument as defined inclaim 1, said bottom surface being provided with at least two depressions; and wherein said guide member includes at least two projecting portions each accommodated and retained in one of said depressions.

5. In a keyboard instrument as defined in claim 4, said guide member having a middle portion constituting said guide portion, and two end portions at opposite ends of said middle portion and each provided with one of said projecting portions.

6. In a keyboard instrument as defined in claim 5, said middle portion including a pair of at least slightly resiliently yieldable strip portions located at and bounding opposite lateral sides of said slot.

7. In a keyboard instrument as defined in claim 1, said guide member having a first portion secured to said key, and a substantially loop-shaped second portion extending from said first portion and constituting said guide portion.

8. In a keyboard instrument as defined in claim 7, said first portion having longitudinally extending edges and transversely extending edges; and wherein said second portion extends from a transversely extending edge of said first portion.

9. In a keyboard instrument as defined in claim 7, wherein said second portion is of bifurcated out-line, said slot having an open end which faces away from said first portion.

10. In a keyboard instrument as defined in claim 1, said key having a rearportion and said bottom surface being provided on said rear portion, said slot extending outwardly beyond said rear portion.

11. In a keyboard instrument as defined in claim 1, wherein said guide portion includes two strips extending longitudinally of said key and bounding said slot,

direction of said key.

a a s 

1. In a keyboard instrument, in combination, at least one elongated key which is movable along a predetermined path, said key having (an external) a bottom surface; a guide member consisting of synthetic plastic material and secured to saiD key for movement therewith, said guide member having a guide portion outwardly adjacent to said (external) bottom surface and completely external from said key, said guide portion provided with an elongated slot extending in the longitudinal direction of said key; a support; and a guide pin mounted on said support adjacent to said key and having a portion extending into said slot for guiding said key during movement along said path.
 2. In a keyboard instrument as defined in claim 1, said bottom surface being provided with a recess, and said guide member being mounted on said bottom surface with said slot extending across said recess.
 3. In a keyboard instrument as defined in claim 2, said recess being substantially cylindrical and having a diameter at least equal to the length of said slot.
 4. In a keyboard instrument as defined in claim 1, said bottom surface being provided with at least two depressions; and wherein said guide member includes at least two projecting portions each accommodated and retained in one of said depressions.
 5. In a keyboard instrument as defined in claim 4, said guide member having a middle portion constituting said guide portion, and two end portions at opposite ends of said middle portion and each provided with one of said projecting portions.
 6. In a keyboard instrument as defined in claim 5, said middle portion including a pair of at least slightly resiliently yieldable strip portions located at and bounding opposite lateral sides of said slot.
 7. In a keyboard instrument as defined in claim 1, said guide member having a first portion secured to said key, and a substantially loop-shaped second portion extending from said first portion and constituting said guide portion.
 8. In a keyboard instrument as defined in claim 7, said first portion having longitudinally extending edges and transversely extending edges; and wherein said second portion extends from a transversely extending edge of said first portion.
 9. In a keyboard instrument as defined in claim 7, wherein said second portion is of bifurcated out-line, said slot having an open end which faces away from said first portion.
 10. In a keyboard instrument as defined in claim 1, said key having a rear portion and said bottom surface being provided on said rear portion, said slot extending outwardly beyond said rear portion.
 11. In a keyboard instrument as defined in claim 1, wherein said guide portion includes two strips extending longitudinally of said key and bounding said slot, said strips being at least slightly yieldable in transverse direction of said key. 